Anomalous Mesozoic thermal regime, central Appalachian Piedmont: evidence from sphene and zircon fission-track dating

Abstract

Near concordance of FTA over a large tract of crystalline basement and within Upper Triassic sediments in the Newark Basin indicates Late Triassic-Early Jurassic total resetting of the fission track clocks followed by regional cooling between sphene (~275 ± 25°C) to zircon (~220 ± 40°C) closure temperatures at rates of ~4-8°C/Ma. Fourteen Rb-Sr whole rock-mica ages, together with previously reported 40Ar/39Ar biotite and hornblende ages, generally indicate no regional Mesozoic resetting. Thus, the maximum temperature experienced by the samples was ~300°C. The FTA, taken together with previously reported denudation history and thermal modeling of the Newark Basin, suggests that the thermal ev..